CN101776435A - Dielectric-capacitance testing method of deformation degree of transformer winding - Google Patents

Abstract

The invention provides a method for measuring the deformation degree of a transformer coil and relates to the technical field of testing electrical components. It is to judge the degree of deformation of the transformer winding by measuring the change of the dielectric loss and capacitance of the transformer coil. The present invention has outstanding beneficial effects: it overcomes the deficiencies of the prior art, and judges the degree of deformation of the transformer winding by measuring the dielectric loss of the transformer coil and the change of the capacitance, using the method that is, through the overall capacitance method or the phase-to-phase capacitance method, Or through the mutual complementation and verification between the two, the degree of deformation of the transformer coil can be judged more accurately, and timely and accurate judgment and monitoring and maintenance of the transformer operating state can be carried out to ensure the normal and safe operation of the transformer, which is conducive to improving the work of the transformer. quality and efficiency. It is especially suitable for testing the deformation degree of transformer coils with a voltage level of 110kV and above.

Description

Capacitance Test Method for Transformer Coil Deformation Degree

technical field

The invention relates to the technical field of testing electrical structural components, in particular to a capacitance-inducing test method for transformer coil deformation degree used in power systems to judge high-voltage levels.

Background technique

At present, the test methods for diagnosing the deformation degree of transformer coils in domestic power systems mainly include the frequency response method and the low-voltage short-circuit impedance method. These two methods are susceptible to field wiring interference and cannot accurately determine the coil deformation position when judging the deformation degree of the transformer coil, so they have certain limitations.

In order to accurately judge the degree of deformation of the transformer coil, a new test method - capacitance method is adopted. The dielectric capacitance method is a new method for judging the deformation degree of the transformer winding by measuring the change of the dielectric loss and capacitance of the transformer coil. As the properties of the transformer coil change, its distribution parameters such as inductance, capacitance, and resistance will also change. The dielectric capacitance method is to judge the degree of coil deformation and the position of the coil deformation according to the size of the transformer coil as a whole and the dielectric loss and capacitance change between the high, medium and low phases and phases.

Contents of the invention

The purpose of the present invention is to provide a transformer coil deformation degree of capacitance test method, by measuring the dielectric loss of the transformer coil and/or capacitance changes, to determine the degree of deformation of the transformer winding, using the method that is through the overall capacitance method or phase-to-phase The capacity-inducing method, or through the mutual complementation and verification between the two, can accurately judge the deformation degree of the transformer coil, timely and accurately judge and monitor and overhaul the transformer operating status, and ensure the normal and safe operation of the transformer, which is conducive to improving The working quality and efficiency of the transformer. It is especially suitable for testing the deformation degree of transformer coils with a voltage level of 110kV and above.

The technical solution of the present invention is: a transformer coil deformation degree capacitance test method, which is characterized in that it is a method for judging the transformer winding deformation degree according to the judgment standard by measuring the dielectric loss and/or capacitance change of the transformer coil.

The method for measuring the capacitance of the deformation degree of the transformer coil is characterized in that during the measurement, the dielectric loss or capacitance measurement between the high, medium and low windings of the transformer and to the ground can be carried out at first, and then the above-mentioned measured value and its initial value are equal to The factory value or handover value is compared, and according to the judgment standard, it is called the overall capacitance method to judge which voltage level winding of the transformer is deformed and the degree of deformation.

The transformer capacitance measurement can refer to: C1 capacitance of low voltage winding to ground, _C2 capacitance between medium and low voltage windings, _C3 capacitance between high and medium voltage windings, _C4 capacitance of medium voltage winding to ground Capacitance, C ₅ capacitance of high voltage winding to ground; C _H+M+L capacitance of high, medium and low voltage windings to ground, C _H+M capacitance of high and medium voltage windings to ground, C _H capacitance of high voltage winding to ground , C _M the capacitance of the medium-voltage winding to the ground, and C _L the capacitance of the low-voltage winding to the ground. The specific calculation of the measurement is as follows: Formula 1-5:

Formula 1, C ₁ =(C _H+M+L +C _L -C _H+M )/2

Formula 2, C ₂ =(C _L +CH _+M -CH _+M+L )/2

Formula 3, C ₃ =(C _M +CH _{-CH +M} )/2

Formula 4, C ₄ (C _H+M+L +C _M -C _{L -CH} )/2

Formula 5, C ₅ =( _CH +CH _{+M -CM} )/2

The comparison of the above measured value with its initial value, i.e. factory value or handover value, refers to: when the error is greater than a certain specified value, it is considered that the transformer is deformed, and monitoring during operation should be strengthened; when the error is greater than another specified value When the transformer is considered to be seriously deformed, effective measures should be taken to strengthen monitoring during operation, and it should be dismantled on site or returned to the factory for inspection.

The judgment standard of the overall capacitance method is: when the calculated capacitance between the high, middle and low windings and the capacitance to the ground respectively and the initial value, that is, the factory value or the handover value, the error is between ±3-6%, the transformer If there is deformation, the monitoring during operation should be strengthened; when the error is greater than ±7%, the transformer is seriously deformed and should be returned to the factory for maintenance.

Described transformer coil deformation degree dielectric capacitance test method is characterized in that when measuring, it is also possible to firstly measure the dielectric loss and capacitance between each phase of the high, medium and low windings, and then use the measured values of the above dielectric loss and capacitance Phase-to-phase comparison is to compare the above measured values horizontally, and judge the degree of deformation of which phase winding of the transformer according to the judgment standard, which is called the phase-to-phase capacitance method.

The measurement of the dielectric loss and capacitance described in the phase-to-phase capacitance method is to measure the high-voltage windings A, B, C to the medium-voltage windings Am, Bm, Cm, and the medium-voltage windings Am, Bm, Cm to the low-voltage windings a, b, and Cm respectively. c, the dielectric loss and capacitance of the low-voltage winding to the iron core;

The phase-to-phase comparison of the measured values of dielectric loss and capacitance described in the phase-to-phase capacitance method can refer to: when the error is greater than a certain specified value, it is considered that the transformer is deformed, and monitoring during operation should be strengthened; when the error is greater than another specified value When the value is higher, the transformer is considered to be seriously deformed, and the monitoring during operation should be strengthened, and it should be dismantled on site or returned to the factory for inspection.

The measurement of the dielectric loss and capacitance described in the phase-to-phase capacitance method can be carried out in this connection mode.

The judgment standard described in the phase-to-phase capacitance method can refer to: when the capacitance phase-to-phase error is between ±3-6% and the dielectric loss is greater than 0.8%, the transformer is deformed, and monitoring during operation should be strengthened; when the capacitance error When it is greater than ±7% and the dielectric loss is greater than 1.2%, the transformer is seriously deformed and should be returned to the factory for repair.

The method for measuring the degree of deformation of the transformer coil is characterized in that during the measurement, it is also possible to: measure the dielectric loss or capacitance between the high, medium and low windings of the transformer and to the ground, and then compare the above measured value with its initial value That is, the error value of the factory value or the handover value is compared, and according to the judgment standard, it is judged which voltage level winding of the transformer is deformed and the degree of deformation is called the overall capacitance method; The measurement of dielectric loss and capacitance, and then compare the above measured values of dielectric loss and capacitance horizontally between phases, and judge the degree of deformation of which phase winding of the transformer according to the judgment standard, which is called the interphase capacitance method; The mutual complementation and verification of each other can more accurately judge the degree of deformation of the transformer coil, and timely and accurately judge and monitor and overhaul the transformer operating status. The specific operations of the overall intervening method and the interphase intervening method can be the same as above.

The present invention has outstanding beneficial effects: it overcomes the deficiencies of the prior art, and by measuring the change of the dielectric loss and/or capacitance of the transformer coil, the method is used to adopt the overall capacitance method or the phase-to-phase capacitance method, or both The mutual complementation and confirmation among them can accurately judge the degree of deformation of the transformer coil, and take effective measures to monitor and overhaul the transformer operating status in time and accurately, so as to ensure the normal and safe operation of the transformer, which is conducive to improving the working quality and efficiency of the transformer. . It is especially suitable for testing the deformation degree of transformer coils with a voltage level of 110kV and above.

The following will be described in detail in conjunction with the accompanying drawings and embodiments, but not as a limitation to the present invention.

Description of drawings

Fig. 1 is a schematic diagram of a three-winding transformer according to an embodiment of the present invention.

FIG. 2 is an equivalent schematic diagram of the transformer in FIG. 1 .

Detailed ways

First, the meanings of the symbols in the figure and in this article are explained as follows: C ₁ --- the capacitance of the low-voltage winding to the ground; tan δ ₁ --- the dielectric loss of the low-voltage winding to the ground; C ₂ --- the capacitance between the medium and low-voltage windings ; tan δ ₂ -- dielectric loss of medium and low voltage windings to ground; C ₃ -- capacitance between high and medium voltage windings; tan δ ₃ -- dielectric loss of high, medium and low voltage windings to ground; C ₄ - - capacitance of medium voltage winding to ground; tan δ ₄ - dielectric loss of medium voltage winding to ground; C ₅ - capacitance of high voltage winding to ground; tan δ ₅ - dielectric loss of high voltage winding to ground; C _{H+ M+L} -- the capacitance of the high, medium and low voltage windings to the ground; tan δ _H+M+L -- the dielectric loss of the high, medium and low voltage windings to the ground; C _H+M the capacitance of the high and medium voltage windings to the ground ; tan δ _H+M -- dielectric loss of high and medium voltage windings to ground; C _H capacitance of high voltage windings to ground; tan δ _H -- dielectric loss of high voltage windings to ground; C _M capacitance of medium voltage windings to ground ; tan δ _M -- dielectric loss of medium voltage winding to ground; C _L capacitance of low voltage winding to ground; tan δ _L -- dielectric loss of low voltage winding to ground; A high voltage winding A phase, B high voltage winding B phase, C High voltage winding C phase; Am medium voltage winding A phase, Bm medium voltage winding B phase, Cm medium voltage winding C phase; a low voltage winding A phase, b low voltage winding B phase, c low voltage winding C phase, O high voltage neutral point winding , Om medium voltage neutral point winding, Yn high voltage winding wiring mode, yn0 medium voltage winding wiring mode, d11 low voltage winding wiring mode; 1--high voltage winding, 2--medium voltage winding, 3--low voltage winding, 4-- Transformer core, 5--transformer casing.

The dielectric capacitance method is to judge the degree of coil deformation and the position of coil deformation according to the magnitude of dielectric loss and capacitance change between the transformer coil as a whole and between high, medium and low phases and phases. The introduction method is divided into two parts: the overall introduction method and the phase introduction method. The overall capacitance method judges which voltage level winding of the transformer is deformed and the degree of deformation, and the phase-to-phase capacitance method judges the degree of deformation of which phase winding. Both the overall dielectric capacitance method and the phase-to-phase dielectric loss method are measured by a high-voltage dielectric loss meter based on the Xilin bridge principle. The overall dielectric capacitance method is to measure the dielectric loss and capacitance between the high, medium and low windings of the transformer and to the ground. Determine which voltage level winding of the transformer is deformed and the degree of deformation. The interphase capacitance method is to measure the dielectric loss and capacitance between each phase of the high, medium and low windings, and judge the degree of deformation of which phase winding.

In the following, three-winding transformers are taken as an example, and the capacitance method for judging the deformation degree of transformer coils is explained. The test data of double-winding transformers does not have the test data of medium-voltage windings. See Figures 1 to 2.

Embodiment 1: overall introduction method

Test wiring: The measuring instrument adopts the high-voltage dielectric loss meter based on the principle of Xilin bridge. And ground dielectric loss and capacitance measurement. Through the test data of the five dielectric losses and capacitances of the high, medium and low windings of the transformer, the capacitance of the low voltage winding to ground; the capacitance between the medium and low voltage windings; the capacitance between the high and medium voltage windings; The capacitance of the voltage winding to the ground; the capacitance and dielectric loss of the high voltage winding to the ground. Through these five dielectric loss and capacitance changes from the factory value, the degree of coil deformation of the voltage level of the transformer coil can be judged. The capacitance and dielectric loss of each part of the test wiring and the tested transformer are shown in Table 1:

Table 1 Test wiring and test results of transformer overall capacitance method

The dielectric loss and capacitance between the transformer coils can be calculated through the data of the dielectric loss and capacitance test of the transformer's high, medium and low voltage windings. Since the overall dielectric loss is not sensitive to reflect the degree of deformation of the transformer winding, conversion is generally not performed, while the capacitance reflects the degree of deformation sensitively and needs to be calculated. The overall capacitance of the transformer coil is calculated separately: C ₁ the capacitance of the low-voltage winding to the ground; C ₂ the capacitance between the medium and low voltage windings; C ₃ the capacitance between the high and medium voltage windings; C ₄ the capacitance of the medium voltage winding to the ground; C ₅ High voltage winding capacitance to ground. The specific calculation is as follows formula 1-5:

Formula 1, C ₁ =(C _H+M+L +C _L -C _H+M )/2

Formula 2, C ₂ =(C _L +CH _+M -CH _+M+L )/2

Formula 3, C ₃ =(C _M +CH _{-CH +M} )/2

Formula 4, C ₄ =(C _H+M+L +C _M -C _{L -CH} )/2

Formula 5, C ₅ =( _CH +CH _{+M -CM} )/2

Judgment standard of the overall capacitance method: when the error between the calculated high, medium and low winding capacitance and the initial value (factory value or transfer value) of the capacitance and the initial value (factory value or handover value) is between ±3-6%, the transformer is deformed. Monitoring during operation should be strengthened; when the error is greater than ±7%, the transformer is seriously deformed and should be returned to the factory for repair.

Embodiment 2: interphase capacity method

In order to accurately detect the degree of deformation of which phase coil of the transformer, the phase-to-phase dielectric loss and capacitance of the winding are tested separately, that is, the high-voltage windings A, B, and C are respectively measured relative to the medium-voltage windings Am, Bm, and Cm phases, and the medium-voltage The windings Am, Bm, and Cm are relatively low-voltage windings a, b, and c-phase, and the dielectric loss and capacitance of the low-voltage winding to the iron core. Most of the 110-220kV transformers operating in the domestic power grid are connected at points Yn, yn0, and d11. The voltage levels of high-voltage windings are 110kV and 220kV, the voltage levels of medium-voltage windings are 35kV and 110kV, and the voltage levels of low-voltage windings are 10kV and 35kV. two kinds. The low-voltage winding connection method is to connect the 11-point connection method inside the transformer, and the transformer leads out the three phases a, b and c respectively. Therefore, the phase-to-phase capacitance method mainly considers the measurement in this connection mode.

Taking the test of transformer high-voltage A-phase winding, medium-voltage Am-phase winding and low-voltage A-phase winding as an example, the measuring instrument adopts the high-voltage dielectric loss meter based on the Xilin bridge principle, and the instrument adopts the positive wiring method for measurement. The test wiring and measurement positions are as shown in Table 2 Wiring is required. The capacitance and dielectric loss of each part of the test wiring and the tested transformer are shown in Table 2:

Table 2 Test wiring and measurement parts of transformer phase-to-phase capacitance method

In the same way, test the dielectric loss and capacitance of the low-voltage windings to the core of the high-voltage windings B and C relative to the medium-voltage windings Bm and Cm, the medium-voltage windings Bm and Cm relative to the low-voltage windings B and C. Through the horizontal comparison among A, B, and C of windings of the same voltage level, the deformation degree of transformer windings can be judged.

Judgment standard of phase-to-phase dielectric capacitance method: when the phase-to-phase error of capacitance is between ±3-6% and the dielectric loss is greater than 0.8%, the transformer is deformed, and monitoring during operation should be strengthened; when the capacitance error is greater than ±7% and the dielectric loss is greater than 0.8%, When the time is greater than 1.2%, the transformer is seriously deformed and should be returned to the factory for repair.

Claims (9)

1. dielectric-capacitance testing method of deformation degree of transformer winding is characterized in that it being variation by measuring transformer coil dielectric loss and/or electric capacity, according to criterion, judges the deformation of transformer winding degree methods.

2. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 1, when it is characterized in that measuring, at first carry out between the high, medium and low winding of transformer and dielectric loss over the ground or electric capacity measurement, the error amount that with above-mentioned measured value and its initial value is factory-said value or handing-over value then compares, according to criterion, judge which electric pressure winding of transformer deforms and deformation extent, is called whole Jie's appearance method.

3. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 2 is characterized in that the measurement of described transformer electric capacity is meant: C ₁Low pressure winding electric capacity over the ground, C ₂In, the electric capacity between the low pressure winding, C ₃Electric capacity between high, the middle pressure winding, C ₄Middle winding electric capacity over the ground, the C of pressing ₅High pressure winding electric capacity over the ground; The formula that specifically the is calculated as follows 1-5 that measures:

Formula 1, C ₁=(C _H+M+L+ C _L-C _H+M)/2

Formula 2, C ₂=(C _L+ C _H+M-C _H+M+L)/2

Formula 3, C ₃=(C _M+ C _H-C _H+M)/2

Formula 4, C ₄=(C _H+M+L+ C _M-C _L-C _H)/2

Formula 5, C ₅=(C _H+ C _H+M-C _M)/2

Described is that the error amount of factory-said value or handing-over value compares and is meant with above-mentioned measured value and its initial value: when error during greater than a certain setting, think that promptly there is distortion in transformer, should strengthen operating supervision; When error during greater than another setting, think that promptly there is gross distortion in transformer, should carry out strip inspection.

4. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 2, it is characterized in that described criterion is: when over the ground electric capacity and initial value between each the high, medium and low winding that calculates and respectively is factory-said value or handing-over value error between ± the 3-6% time, there is distortion in transformer, should strengthen operating supervision; When error greater than ± 7% the time, there is gross distortion in transformer, should adopt an effective measure and strengthen operating supervision, disintegrates at the scene or returns factory and check.

5. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 1, when it is characterized in that measuring, at first carry out the every alternate dielectric loss of high, medium and low winding and the measurement of electric capacity, measured value with above-mentioned dielectric loss and electric capacity carries out alternate lateral comparison then, according to criterion, judge the degree of which phase winding distortion of transformer, be called alternate Jie and hold method.

6. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 5, the measurement that it is characterized in that described dielectric loss and electric capacity is meant, measure high pressure winding A, B, C centering pressure winding Am, Bm, Cm respectively, middle winding Am, Bm, the Cm of pressing is to low pressure winding a, b, c, and the low pressure winding is to the dielectric loss and the electric capacity of iron core.

7. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 5, the measured value that it is characterized in that described dielectric loss and electric capacity carries out alternate lateral comparison and refers to: when error during greater than a certain setting, think that promptly there is distortion in transformer, should strengthen operating supervision; When error during greater than another setting, think that promptly there is gross distortion in transformer, should carry out strip inspection.

8. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 5, it is characterized in that described criterion is: when the alternate error of electric capacity between ± the 3-6% and during dielectric loss greater than 0.8% the time, there is distortion in transformer, should strengthen operating supervision; When capacitance error greater than ± 7% and during dielectric loss greater than 1.2% the time, there is gross distortion in transformer, should adopt an effective measure and strengthen operating supervision, disintegrates at the scene or returns factory and check.

9. dielectric-capacitance testing method of deformation degree of transformer winding according to claim 1, when it is characterized in that measuring, carry out between the high, medium and low winding of transformer and dielectric loss over the ground or electric capacity measurement, the error amount that with above-mentioned measured value and its initial value is factory-said value or handing-over value then compares, according to criterion, judge which electric pressure winding of transformer deforms and deformation extent, is called whole Jie's appearance method; Simultaneously, also carry out the every alternate dielectric loss of high, medium and low winding and the measurement of electric capacity, the measured value with above-mentioned dielectric loss and electric capacity carries out alternate lateral comparison then, according to criterion, judge the degree of which phase winding distortion of transformer, be called alternate Jie and hold method; By replenishing mutually and confirmation of the two, more can judge the deformation extent of transformer coil more exactly, judge and carry out the supervision and the maintenance of transformer running status timely and accurately.

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